A slab of meat, with the dimensions $20cm15cm10cm,$ is to be frozen between refrigerated plates with the plate temperature at $-34C.$ The meat is packaged in cardboard $1\mathrm{.}5mm$ thick on either side of the slab. Using Plank's equation, calculate the freezing time $($in second$)$ if the cardboard were present on the slab. Assume that for the plate freezer, the surface heat$-$transfer coefficient is $600\frac{J}{m^2.s.C},$ the thermal conductivity of cardboard is $0\mathrm{.}06\frac{J}{m.s.C},$ the thermal conductivity of frozen meat is $1\mathrm{.}6\frac{J}{m.s.C},$ its latent heat of fusion is $256k$j$/$kg water and the density is $1090\frac{kg}{m^3}.$ The meat contains $75\%$ moisture. Assume also that meat freezes at $-2C,P=0\mathrm{.}24,R=0\mathrm{.}065.$

L$$tfen birini se$$in:

a$.6842$

b$.7500$

c$.6200$

d $\mathrm{.}3421$

e $\mathrm{.}4156$